1. Technical Field
The present disclosure relates to electrosurgical instruments and methods for performing surgical procedures and, more particularly, to an electrosurgical vessel sealing instrument with a jaw assembly having one or more insulating members associated with the sealing plate that provide reduced thermal spread and reduced edge cutting while enabling improved dimensional tolerances during the prototyping and manufacturing process.
2. Background of Related Art
A hemostat or forceps is a simple pliers-like tool that uses mechanical action between its jaws to constrict tissue and is commonly used in open surgical procedures to grasp, dissect and/or clamp tissue. Electrosurgical forceps utilize both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize and/or seal vascular tissue.
Using electrosurgical forceps, a surgeon can elect to seal, cauterize, coagulate, or desiccate tissue, or simply reduce or slow bleeding by controlling the intensity, frequency and duration of the electrosurgical energy applied to the tissue. Generally, the electrical configuration of electrosurgical forceps can be categorized in two classifications: 1) monopolar electrosurgical forceps; and 2) bipolar electrosurgical forceps.
Monopolar forceps utilize one active electrode associated with the clamping end effector and a remote patient return electrode or pad that is attached externally to the patient, e.g., on the leg or buttocks. When electrosurgical energy is applied, the energy travels from the active electrode, to the surgical site, through the patient, and to the return electrode.
Bipolar electrosurgical forceps utilize two generally opposing electrodes that are generally disposed on the inner facing or opposing surfaces of the end effectors (e.g., jaws of the instrument) which are, in turn, electrically coupled to an electrosurgical generator. Each electrode is charged to a different electric potential. Since tissue is a conductor of electrical energy, when the end effectors are utilized to clamp or grasp tissue therebetween, the electrical energy can be selectively transferred through the tissue to cause a change therein and effect sealing of the vessel.
Certain surgical procedures require sealing blood vessels or vascular tissue. The term “vessel sealing” is defined as the process of liquefying the collagen in the tissue so that the tissue cross-links and reforms into a fused mass. In order to form a burst-resistant and sound vessel seal, the application of sealing energy should be targeted to the specific region of tissue to be sealed. Excessive thermal energy should not be allowed to spread to adjacent areas of tissue, as this may diminish the integrity of a resulting seal since the energy required to form the seal is dissipated into the surrounding tissue rather than into the region intended to be sealed. For the purposes herein the term “thermal spread” refers generally to the heat transfer (heat conduction, heat convection or electrical current dissipation) dissipating along the periphery of the electrically conductive or electrically active surfaces of an electrosurgical instrument to adjacent tissue. This can also be termed “collateral damage” to adjacent tissue. One form of collateral damage is referred to as “edge cutting” whereby current concentrations near the edge of the electrode partially or completely sever the vessel being sealed. The reduction and control of such thermal spread and attendant collateral damage is therefore a desirable objective in the design of a vessel sealing instrument.